This invention relates to methods and apparatus for removing skin from the torso of an animal and, in particular, to such methods and apparatus for the skin has variations in thickness around the torso.
In many commercial meat packing operations, the skin is usually removed from the animal carcass by pulling, or in some instances, the animal is butchered and the skin is removed thereafter from the primal cuts. However, when the skin is pulled from the carcass, a substantial amount of fat is sometimes removed with the skin. The fat must then be removed from the skin. Further, removal of the skin from primal cuts involves time consuming operations and involves the use of costly equipment.
Apparatus for removing the skin from the torso of an animal carcass, such as a hog, are well known in the art. An example is described in U.S. Pat. No. 4,351,088, Leining et al, Method and Apparatus For Removing Skin From Animal Carcasses, assigned to George A. Hormel Company. Leining et al ""088 discloses an apparatus and method for removing the torso portion of the skin from the carcass of an animal, such as a hog. The apparatus includes an overhead support from which a carcass is suspended during the skin removing operation. The skin is first removed from the hind quarters of the carcass and then a cut is made in the skin of the torso completely around the carcass just rearwardly of the fore limbs. A flap forming blade makes a longitudinal cut in the carcass and the longitudinal edge of the skin defined by the longitudinal cut is gripped by revolvable toothed cylinders carried by a revolvable drum to form a flap which is wound about the toothed cylinder. A carcass engaging device holds the carcass against the drum during the flap forming operation. A flexible pressurized movable blade positioned adjacent the drum progressively cuts the skin from the carcass as the drum is revolved.
In many skin removal apparatus, the skin is removed by first peeling the skin back with a knife. A dull blade is then inserted between the peeled flap of skin and the carcass. As the carcass rotates, the dull blade peels the skin from the carcass. The dull blade is positioned a distance away from the carcass so that the skin from the carcass can pass between the dull blade and rotating cylinder. The distance which the dull blade is so positioned is known as the dull blade gap distance.
To account for variations in the thickness of the skin of the animal around the carcass as the carcass rotates, it is common to allow the dull blade to float permitting variations in the dull blade gap distance.
U.S. Pat. No. 6,086,470, Ranniger, Skinning Machine, and U.S. Pat. No. 5,766,066, Ranniger, Skinning Machine, disclose automatic skinning machines. A cutting shoe is adjustable by a camming structure to automatically move the cutting shoe between an initial position and a cutting position. In addition, the cutting shoe is mounted in a floating manner such that it can self adjust to different thicknesses of product flowing therethrough.
U.S. Pat. No. 4,272,862, Griffin et al, Skinning Apparatus, discloses a skinning apparatus with a cushioned, spring biased, cutting knife making it free to move slightly through a defined area and against a yieldable bias force.
U.S. Pat. No. 4,369,547, Robertson et al, Animal Skinning Machine, discloses an animal skinning machine with means to adjust the cutting depth of a knife as irregularities in the skin pass the knife. A resiliently cupped spring washer urges a roller against the skin and, if there are irregularities in the skin, the spring washer can be compressed to permit the roller to retract sufficiently to pass the irregularities.
In these apparatus, a passive biased, e.g., spring or resilient means, blade floats to permit variations in thickness of the skin of the carcass of the animal be skinned.
Alternatively, U.S. Pat. No. 4,979,269, Norrie, Method and Apparatus For Separating Back Fat From Loins, discloses a conveyor type skinning apparatus using an optical sensor to adjust the spacing between the conveyor and a skinning blade. A pressure device applies pressure to the upper surface of a loin portion. A generally arcuate blade is interposed between the conveyor and the pressure device, the blade being movable relative to the conveyor. The thickness of the back fast on the loin portion between the conveyor and the lean portion of the loin is sensed generating measurement signals thereby moving the blade. In order to position the blade as accurately as possible, a video camera and light source is provided alongside the conveyor, adjacent or slightly downstream of the position of the first of two pressure rolls. The camera functions to observe and sense the thickness of the portion of fat the loin lying lowermost on the conveyor as it approaches the knife blade. The knife can then be adjusted automatically.
The above-described methods and apparatus, however, still do not effectively adjust the dull blade gap in order to maximize the amount of lean left on the carcass while minimizing tearouts. If the dull blade gap is too large a portion of the lean meat of the carcass is removed along with the skin. This results in inefficiency. In the case of a hog, bacon is taken from the belly were the skin is thin. If the dull blade gap is not effectively set small over the belly portion of a hog, valuable bacon will be removed along with the skin. However, if the dull blade gap is not set thicker over the back portion of the hog, the skin will often tear out of the skinning machine preventing the efficient removal of the skin from the carcass of the animal.
Floating blades do not effectively adjust the dull blade gap thickness. Further, even skinning systems which attempt to major thickness of the skin been removed are subject to inaccuracies and inefficiencies due to inaccurate or ineffective measurement. It has been found that greater efficiencies can be obtained by using the present invention.
The present invention solves the inefficiency inherent in skinning systems with floating blades and measured systems. In an apparatus which is configured to repeatedly remove the skin from the torso portion of the carcass of a particular animal, it has been found that the thickness of the skin around the circumference of the carcass is relatively consistent from animal to animal. Thus, the dull blade gap distance can be predetermined and an apparatus for removing the skin from torso portion of the carcass of an animal may be preconfigured with dull blade gap distances which vary in accordance with the position around the circumference of the carcass contacted by the dull blade. These preset dull blade gap distances provide the most effective mechanism to preserve as much of the lean meat of the animal as possible while minimizing tearouts.
In an embodiment, the present invention provides a method of removing skin from an animal having a torso using an apparatus having a rotatable drum having a circumference, a gripper positioned at a point on the circumference of the rotatable drum adapted to engage a portion of the skin causing the carcass of the animal to rotate as the rotatable drum rotates, a sharp blade positioned near the point on the circumference of the rotatable drum for cutting the skin from the animal, a dull blade spaced a dull blade gap distance away from the circumference of the rotatable drum and a setback distance away from the sharp blade opposite from the gripper, the dull blade adapted to contact the skin of the animal as the animal rotates. A portion of the skin of the torso of the animal is gripped by the gripper. The drum is rotated causing the torso of the animal to rotate forcing the dull to peel the skin from the torso of the animal as the torso of the animal contacts the dull blade. The dull blade gap distance is adjusted in accordance with a predetermine profile which varies around the torso of the animal.
In a preferred embodiment, the skin of the hog is thicker around certain parts of the torso of the animal than around other parts of the torso of the animal and the adjusting step adjusts the dull blade gap distance wider where the certain parts of the torso of the animal are thicker and narrower where the other parts of the torso of the animal is thinner.
In a preferred embodiment, the hog has a stomach and a back, wherein the skin is thinner on the stomach, wherein the skin is thicker on the back, and the adjusting step the adjusts the dull blade gap distance narrower when the dull blade contacts the stomach of the hog and wider when the dull blade contacts the back of the hog.
In a preferred embodiment, the torso of the hog has a teat area, a flank and a back and the adjusting step adjusts the dull blade gap (a) narrower when the dull blade contacts the teat area of the hog, (b) wider when the dull blade contacts the flank of the hog, (c) narrower when the dull blade contacts the torso of the hog between the flank and the back of the hog, (d) wider when the dull blade contacts the back of the hog, and (d) narrower when the dull blade gap contacts the torso of the hog between the back and the teat area of the torso of the hog.
In a preferred embodiment, the animal is a hog.